JP3162507B2 - Optical recording medium and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a single-plate type optical recording medium having a recording layer of a dye capable of recording large-capacity information and having a high reflectance, and a method of manufacturing the optical recording medium.

[0002]

2. Description of the Related Art A single-plate recordable and commercially available compact disk (hereinafter referred to as a CD) having a recording layer formed of a dye and a metal reflection layer provided on the recording layer in order to increase the reflectivity and further having a protective layer provided thereon. Optical recording media compatible with players are, for example, OpticalData Storage 1989 Techni.
cal Digest Series Vol.1 45 (1989), JP-A-2-132656,
It has been proposed in JP-A-2-168446 and the like.

[0003] In this optical recording medium, a protective layer is provided on the reflective layer to protect the recording layer and the reflective layer. A hard resin called a hard coat is usually used for the protective layer in order to prevent the recording layer and the reflective layer from being damaged. Further, the function of the protective layer is to prevent the recording layer and the reflective layer from peeling off, and to prevent the recording layer and the reflective layer from being oxidized and degraded, thereby helping to improve the durability. Therefore, the protective layer is required to have good adhesion to the reflective layer.

However, in a medium using a dye for the recording layer, the recording layer is generally formed by a spin coating method. Although there is a groove on the inner peripheral portion of the optical disk substrate, when the recording layer is formed by the spin coating method, the recording layer is formed on the entire surface from the inner side to the outer side of the groove on the inner peripheral portion of the substrate. When the adhesion between the protective layer and the reflective layer is taken into consideration as described above, for example, the recording films at the inner and outer peripheral portions are removed as proposed in JP-A-2-183442 and JP-A-2-236833. In addition, it is required that the protective layer be formed over the recording layer and the reflective layer.

As described above, in order to form the protective layer over the recording layer and the reflective layer, the portion where the substrate is exposed outside the outermost and innermost circumferences where the recording layer is formed is required. Must be provided. To this end, conventionally, the recording films on the outer peripheral portion and the inner peripheral portion (that is, the outer peripheral portion and the inner peripheral portion from which the recording film is to be removed) are removed after forming the recording layer. Thus, in order to remove the recording film on the outer peripheral portion, the recording film can be easily removed by, for example, dropping a solvent on the outer peripheral portion while rotating the substrate. On the other hand, the removal of the recording layer of the inner peripheral portion cannot be removed by the same method as the case of the outer peripheral portion.For example, it has to be removed by wiping or burning with a laser as disclosed in JP-A-2-183442. Was. However, according to our studies, any of these methods is not only complicated and inferior in productivity, but also cannot completely remove the recording film. For this reason, the adhesion of the protective layer is not sufficient, and when the medium is left for a long time under conditions of high temperature and high humidity, the peel strength of the inner peripheral portion is reduced. We found that there was a problem of causing

As another method of removing the recording layer at the inner peripheral portion,
As disclosed in JP-A-2-236833, there is a method in which a reflective layer is formed without passing over the recording layer, and then the recording layer protruding from the reflective layer on the inner peripheral portion is washed away with a solvent. We have found that this method has the disadvantage that the reflective layer is immersed in the solvent. Since the reflective layer is a thin metal film, it has been found that the reflective layer is damaged when immersed in a solvent, and has a drawback that the reflective layer peels off and noise of the medium increases. Further, this method not only requires a complicated solvent washing step, but also lowers productivity.

[0007]

SUMMARY OF THE INVENTION The present inventors have found that the protective layer has excellent adhesion to the reflective layer. A single-plate optical recording medium that does not peel from the part
Various studies were conducted to develop a method of manufacturing an easy and highly productive method. As a result, the residual stress in the protective layer and the like in the outer peripheral portion and the inner peripheral portion is different, and it is noticed that there is an important fact that the residual stress in the inner peripheral portion is much smaller. A reflective layer is formed over the reflective layer, and a protective layer is further formed over the reflective layer, while the inner peripheral portion is formed if the protective layer is formed over the recording layer and the reflective layer, that is, the reflective layer is The present inventors have found that it is not necessary to exceed the recording layer, and have completed the present invention.

[0008]

That is, the present invention relates to an optical recording medium in which a recording layer, a reflective layer, and a protective layer are laminated on a transparent resin substrate in this order. In addition, a region having no recording layer (for example, 4 and 6 ′ in FIG. 4) is provided on the outer peripheral portion, and a recording layer containing a dye is provided in a region other than the region. In addition, a metal reflective layer is provided such that the inner peripheral portion substantially coincides with the end of the recording layer, and the outer peripheral portion is provided beyond the recording layer. A method of manufacturing an optical recording medium having a protective layer provided on both sides of a reflective layer beyond a reflective layer, and an optical recording medium in which a recording layer, a reflective layer, and a protective layer are laminated in this order on a transparent resin substrate. After providing a recording layer containing a dye on the substrate by a coating method, preferably a spin coating method, By removing the recording layer near the outermost periphery of the plate, a portion where the substrate surface is exposed is provided inside the outermost periphery of the substrate, and then a metal reflective layer is formed on this recording layer, and the inner periphery is In order to protrude the recording layer, the outer peripheral portion is provided so as to extend beyond the recording layer, and the outermost peripheral portion is provided with a region having no reflective layer, and further on the reflective layer, the inner peripheral portion is provided with the recording layer. From the area provided or beyond the recording layer,
On the other hand, a method for manufacturing an optical recording medium in which the outer peripheral portion is coated with a liquid resin that dissolves the substance of the recording layer after applying the liquid resin dissolving the substance of the recording layer to the outermost peripheral portion of the substrate beyond the reflective layer, It is.

FIGS. 1 to 4 are views showing a process of forming an optical recording medium of the present invention. FIG. 1 is a cross-sectional view showing an example of a structure from an inner peripheral portion to an outer peripheral portion in a process of providing a recording layer on a substrate of the optical recording medium of the present invention, and FIG. FIG. 3 is a cross-sectional view showing an example of the structure in the process of removing the layer, FIG. 3 is a cross-sectional view showing an example of the structure in the process of providing the reflective layer on the recording layer after the process of FIG. 2, and FIG. 1 is a sectional view showing an example of the structure of the optical recording medium of the present invention in which a protective layer is provided. FIG. 5 is a sectional perspective view showing an example of the structure of the optical recording medium of the present invention. The following description will be more easily understood by appropriately referring to this drawing. Here, 1 is a substrate, 2 is a recording layer, 3 is a fixing groove of a stamper, 4 is a recording layer removal area on the outermost periphery,
5 is a reflective layer, 6 is a recording layer protruding from the innermost peripheral reflective layer, 4 'is a region where the outermost peripheral reflective layer is not provided, 7 is a protective layer, and 6' is a liquid for the protective layer. An area 1 ′ where the recording layer is dissolved and removed by the resin indicates an outer peripheral side surface of the substrate. Note that the outer peripheral portion refers to the outermost peripheral portion of the substrate and the vicinity near the inner side.

As the transparent resin substrate used in the present invention, a transparent resin substrate that transmits light for recording and reading out signals is preferable. It is desirable that the light transmittance is 85% or more and the optical anisotropy is small. For example, a substrate using a thermoplastic resin such as an acrylic resin, a polycarbonate resin, a polyamide resin, a vinyl chloride resin, or a polyolefin resin is a preferred example. Among these, an acrylic resin, a polycarbonate resin, and an injection-molded resin substrate of a polyolefin resin are preferable from the viewpoint of mechanical strength of the substrate, ease of imparting grooves and prepits, and economic efficiency, and particularly, a polycarbonate resin substrate. Is most preferred.

The shape of these substrates may be plate-like or film-like, circular or card-like. The surfaces of these substrates have grooves for controlling the recording position.
Also, a pit or the like may be partially provided. Such grooves, pits, and the like are preferably provided when a substrate is formed by injection molding, compression molding, or casting. In order to provide grooves and pits during molding of the substrate, a stamper may be mounted in a mold of a molding machine and transferred. In addition, a concave groove formed by a stamper fixing jig is formed on the inner peripheral portion of the substrate made by injection molding.

In the optical recording medium of the present invention, a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on the transparent resin substrate. The dye used is a polymethine dye, a phthalocyanine dye, a naphthalocyanine dye, a naphthoquinone dye,
Dyes having absorption in the oscillation wavelength range of a semiconductor laser, such as azulene dyes and dithiol metal complex dyes, may be mentioned. These dyes improve solubility in solvents,
It may be substituted with various substituents for improving recording characteristics and the like. These dyes can be used alone or in combination of two or more. Of these dyes, phthalocyanine dyes and naphthalocyanine dyes are preferable in consideration of the durability of the dye.

In the present invention, the recording layer containing the above-mentioned dye can be formed by a usual coating method. Among the coating methods, the spin coating method is preferable.

When the dye is formed into a film by a coating method, a solvent that does not damage the resin substrate, that is, a solvent that does not substantially dissolve the resin for the substrate, for example, an aliphatic solvent such as hexane, heptane, octane, decane, and cyclohexane. And alicyclic hydrocarbon solvents, diethyl ether, dibutyl ether,
The dye may be dissolved in a non-polar solvent such as an ether-based solvent such as diisopropyl ether or an alcohol-based solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, and methyl cellosolve.

The above-mentioned dye solution may be applied by a coating method, preferably a spin coating method, for example, in the case of an injection-molded resin substrate, over the entire surface of the substrate outside the groove formed by a stamper fixing jig on the inner periphery. For example, as shown in FIG.

Next, in the present invention, the recording film at the outermost peripheral portion is removed with a solvent in order to provide a portion where the substrate is exposed at the outermost peripheral portion (portion 4 in FIG. 2). As a method for removing the solvent, there is a method in which a solvent is dropped on a portion where the recording film is to be removed near the outermost peripheral portion while rotating the substrate. The solvent used at this time is preferably a solvent that dissolves the dye in an amount of 3% by weight or more.

Specific examples of the solvent used for removing the recording layer are as follows: the above-mentioned solvent, carbon tetrachloride, chloroform,
Halogen solvents such as methylchloroform, 1,12-trichloroethane, tocrilen, and dichloromethane; hydrocarbon solvents such as benzene, toluene, and xylene; ketone solvents such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl keto; butyl cellosolve, and ethyl cellosolve; Examples thereof include alcohol solvents, ester solvents such as butyl acetate, amyl acetate, and cellosolve acetate.
These solvents can be used alone or in combination of two or more.

When forming a recording layer containing a dye,
In addition to the above-mentioned dyes, resins such as nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, urethane resin and the like, leveling agents, defoaming agents and the like are used in a range that does not impair the effects of the present invention, for example, 20% by weight or less, preferably 10% by weight or less.
It can also be used in combination at a weight percent or less.

Next, in the present invention, a reflective layer is provided on the recording layer. Usually, this reflective layer is preferably a thin metal film. In the present invention, in consideration of compatibility with a normal CD player, it is preferable that the reflectance of the medium on the groove be 60% or more. Preferred metals are aluminum,
Examples include gold, silver, copper, platinum, nickel, and alloys containing these metals as one component. The reflective layer of these metals can be formed by a method such as vapor deposition or sputtering. or,
The thickness of these reflective layers is usually preferably about 500 to 2000A. The reflection layer 5 is provided so that the recording layer protrudes at the inner peripheral portion (portion 6 in FIG. 3; in the case of a circular substrate, the recording layer is exposed in an annular shape), while the outer peripheral portion is provided. It is provided so that a region (4 'in FIG. 3) having no reflective layer is provided over the recording layer and at the outermost periphery. In the case of a circular substrate, the film is formed such that a portion where the substrate is annularly exposed remains on the outermost peripheral portion.

Next, a protective layer 7 is further provided on the reflective layer in order to protect these metal reflective films. A liquid resin is usually used for the protective layer. That is, a film can be formed by applying a liquid resin and then curing the resin.
At this time, an ultraviolet curable resin is particularly preferable in terms of productivity and the like. The thickness of the protective layer is preferably about 1 to 15 μm. When forming this protective layer, as shown in FIG. 4 (partially in FIG. 3), the innermost periphery is formed from a region (6) where the recording layer is provided, or a region inward beyond the recording layer. Then, the ultraviolet curable resin is applied to the outer peripheral portion of the substrate over the reflective layer to the outermost peripheral portion of the substrate (the exposed portion of the substrate, 4 ') or the outer peripheral side surface of the substrate (1'). After application, it may be cured by irradiation with ultraviolet rays. For example, when applying a liquid resin for the protective layer to a substrate having a groove by a stamper fixing jig by using a coating method, preferably a spin coating method,
Drop the liquid resin on the outside of the groove of the stamper fixing jig,
What is necessary is just to rotate and apply to the entire surface of the substrate. By applying in this manner, the recording layer protruding from the reflective film at the innermost peripheral portion is dissolved and removed by the liquid cured resin,
The protective layer 7 is formed over the recording layer and the reflective layer (FIG. 4).
6 '). On the other hand, the outer periphery is provided with a portion where the substrate is exposed at the outermost periphery, so that the protective layer 7 is formed over the recording layer and the reflective layer (4 in FIG. 4). Therefore, as the liquid resin used for the protective layer, it is preferable to select a resin that can dissolve the recording layer material in an uncured state at 0.5% by weight or more, preferably 1% by weight or more. Further, from the viewpoint of adhesion between the protective layer and the substrate, the liquid resin for the protective layer is preferably a resin capable of dissolving the substrate resin in an uncured state at 0.5% by weight or more, and more preferably a resin capable of dissolving 1% by weight or more. preferable.

In the present invention, in the process of forming the reflective layer, most of the recording layer protruding from the reflective layer on the inner periphery is coated with the liquid resin for the protective layer. Although it is preferable to dissolve and remove the resin, it is not always necessary to completely remove the resin. In particular, if the liquid resin is a resin capable of dissolving the substrate resin to some extent, the liquid resin also dissolves the substrate while penetrating the remaining recording layer, which is effective in improving the adhesion between the protective layer and the substrate.

Therefore, the UV-curable resin used for the protective layer contains the recording layer material in an uncured state in an amount of 0.5% by weight or more,
Preferably, a resin that dissolves at least 1% by weight is preferred. Therefore, from the viewpoint of the adhesion between the protective layer and the substrate,
UV curing resin is 0.5% by weight of substrate resin in uncured state
As described above, a resin that dissolves more preferably 1% by weight or more is preferable. FIG. 5 is a cross-sectional perspective view showing an example of the structure of the optical recording medium of the present invention thus formed.

The optical recording medium of the present invention irradiates a laser beam through a substrate to record and read out a signal. The wavelength of the laser beam used is preferably a semiconductor laser having an oscillation wavelength of usually 640 to 850 nm. When recording, the output of the laser on the recording film is 5 to 10 while rotating the medium.
The reading should be about mW, and when reading out, the output of the laser should be about 1/10 that of recording. The optical recording medium of the present invention can be printed on the protective layer.

[0024]

EXAMPLES The present invention will be described below in more detail with reference to examples, but embodiments of the present invention are not limited thereto. Example 1 Pd-tetra was formed outside the stamper fixing groove on the grooved surface of an injection molded polycarbonate resin substrate having a spiral groove (depth 140 nm, width 0.5 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 120 mm. -After dropping a 3.5% by weight octane solution of (tt-butyl-cyclohexyloxy) phthalocyanine bromide (average 3.0 / molecule) dye, the resin substrate was cooled at a speed of 1500 rpm.
Rotated for 10 seconds.

After further rotating at 3000 rpm for 20 seconds, octane was dropped on the outermost peripheral recording layer of the substrate while rotating the substrate, and the outermost peripheral recording layer was removed. Next, the resin substrate on which the recording film was formed was dried in an atmosphere at 40 ° C. for 10 minutes. In this way, a recording layer substantially consisting only of a phthalocyanine dye was formed from the outside of the inner peripheral portion to the stamper fixing groove and from the outside of the groove to the region 1.5 mm inside from the outermost edge of the substrate. .

On this recording layer, a reflective layer having a thickness of 80 nm
Was formed by sputtering. However, in this case, the outer peripheral portion exceeds the recording layer and has a width of about 1 mm from the outermost peripheral portion.
On the other hand, in the inner peripheral portion, the reflective layer was not formed in a width of about 1 mm outside the stamper fixing groove of the substrate (that is, the dye layer equivalent to 1 mm was left).

Further, on this reflective layer, an ultraviolet curable resin (Dainippon Ink Product, SD-17) was applied to the entire outer surface of the stamper fixing groove at the inner periphery by spin coating. Next, the entire surface of the resin was irradiated with ultraviolet rays (mJ) and cured to form a protective layer. The thickness of this protective layer was about 7 μm. Also, when applying UV curable resin,
The part of the recording film that protrudes from the innermost reflective layer is contacted with and dissolved by the ultraviolet curable resin, and the ultraviolet curable resin in which a minute amount of the dye constituting the recording layer is dissolved is applied. It was formed beyond the layer. Also, the protective layer was formed on the outermost periphery beyond the recording layer and the reflective layer. When the inner and outer peripheral portions of the medium manufactured in this manner were observed with a microscope from the substrate side and the protective layer side, the reflective layer exceeded the recording layer by about 0.5 mm at the outer peripheral portion, and the protective layer exceeded the reflective layer. About 1m
m, the film was formed up to the outer peripheral edge of the substrate. on the other hand,
It was confirmed that a reflective layer was formed on the inner peripheral portion up to a position where the recording layer and the end portion were substantially the same, and that the protective layer was formed about 1 mm beyond the recording layer and the reflective layer.

In order to evaluate the adhesion of the protective layer of the medium manufactured as described above, an initial and durability test was carried out.
After leaving the tape under the conditions of 90 ° C. and 90% RH for 2000 hours, a tape peeling test was carried out, but no peeling of the protective layer occurred at all in the initial stage and after the durability test.

When the solubility of the ultraviolet curable resin in the uncured state with respect to the dye and the substrate resin was examined, all were dissolved in 1% by weight or more. Comparative Example 1 Instead of the dye used in Example 1, Pd-tetra- (4-methyl-
A medium was prepared in the same manner as in Example 1, except that a 3.5% by weight octane solution of a pentane-2-oxy) phthalocyanine bromide (average of 3.0 / molecule) was used. The dye used in this medium was hardly dissolved in the used ultraviolet curable resin, and the innermost recording layer was not removed and remained off the reflective layer. Therefore, in the innermost peripheral portion, the protective layer was not formed beyond the recording layer. Using this medium, the adhesion of the protective layer was evaluated in the same manner as in Example 1. In the initial peeling test, the protective layer did not peel off at all, but after the moist heat resistance test, the outermost peripheral portion did not peel off, but the innermost peripheral portion peeled off. Comparative Example 2 After a reflective layer was formed in the same manner as in Example 1, octane was dropped on the inner peripheral portion while rotating the substrate to remove the inner peripheral recording layer. The protruding recording layer at the inner peripheral portion was removed, but wrinkles occurred on the reflective layer, which was thought to be due to peeling of the reflective layer. This means
This indicates that it is difficult to completely remove the recording layer protruding from the reflective layer on the inner peripheral portion with a solvent. Example 2 Instead of the dye solution used in Example 1, Pd-tetra
-In the same manner as in Example 1 except that a solution of 3.2% by weight of a brominated (2,4-dimethyl-pentan-3-oxy) phthalocyanine phthalocyanine (average: 3.5 per molecule) dye was used. To produce a medium, and the adhesion of the protective layer was evaluated. No peeling of the protective layer occurred at both the initial stage and after the durability test. The dye was also dissolved in the uncured UV-curable resin in an amount of 1% by weight or more.

[0030]

As is clear from the examples, the recording layer containing the dye is provided in the area other than the area having no recording layer provided on the inner peripheral part and the outer peripheral part, respectively. A metal reflective layer is provided on the inner peripheral portion so as to coincide with the end portion of the recording layer, and the outer peripheral portion extends beyond the recording layer. Further, both the inner peripheral portion and the outer peripheral portion exceed the reflective layer on this reflective layer. It is clear that the provision of the protective layer provides excellent adhesion of the protective layer even when the medium is left for a long period of time under high temperature and high humidity conditions.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a structure from an outer peripheral portion to an inner peripheral portion in a process in which a recording layer is provided on a substrate of a medium of the present invention.

FIG. 2 is a cross-sectional view showing an example of a structure in a process in which a recording layer on an outer peripheral portion is removed after a recording layer is provided on a substrate of a medium of the present invention.

FIG. 3 is a cross-sectional view showing an example of a structure in a process of providing a recording layer on a substrate of the medium of the present invention, removing a recording layer on an outer peripheral portion, and then forming a reflective layer on the recording layer.

FIG. 4 is a sectional view showing an example of the structure of the optical recording medium of the present invention.

FIG. 5 is a sectional perspective view showing an example of the structure of the optical recording medium of the present invention.

[Explanation of symbols]

Reference Signs List 1 substrate 1 'substrate outer peripheral side surface 2 recording layer 3 stamper fixing groove 4 outermost peripheral recording layer removal region 4' outermost peripheral region where reflective layer is not provided 5 reflective layer 6 protrudes from innermost peripheral reflective layer Recording layer 6 'Region where recording layer is dissolved and removed by liquid resin for protective layer 7 Protective layer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-10248 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/24 G11B 7/26

Claims (9)

(57) [Claims] Claims: 1. A recording layer, a reflection layer,
An optical recording medium laminated in the order of a protective layer, wherein an inner peripheral portion and an outer peripheral portion on the substrate each have a region having no recording layer, and a region other than the region contains a dye. A recording layer is provided, and a metal reflective layer is provided on the recording layer such that the inner peripheral portion substantially coincides with the end of the recording layer, and the outer peripheral portion is provided beyond the recording layer, An optical recording medium further comprising a protective layer provided on the reflective layer so as to extend beyond the reflective layer in both the inner peripheral portion and the outer peripheral portion. 2. A recording layer, a reflective layer,
A method for manufacturing an optical recording medium having a protective layer laminated in this order, wherein a recording layer containing a dye is provided on the substrate by a coating method, and then the recording layer near the outermost peripheral portion of the substrate is removed. By providing a portion where the substrate surface is exposed inside the outermost periphery of the substrate, a metal reflective layer is then formed on the recording layer, the inner periphery is such that the recording layer protrudes, and the outer periphery is the recording layer. Is provided so as to provide a region having no reflective layer on the outermost peripheral portion, and further on the reflective layer, the inner peripheral portion is provided from the region where the recording layer is provided or beyond the recording layer. On the other hand, a method for manufacturing an optical recording medium in which a liquid resin dissolving the substance of the recording layer is applied to the outer peripheral portion beyond the reflective layer to the outermost peripheral portion of the substrate, and then the liquid resin is cured to form a protective layer. . 3. The method according to claim 2, wherein the liquid resin used for the protective layer is an ultraviolet curable resin. 4. The method according to claim 2, wherein the liquid resin used for the protective layer is applied by a spin coating method. 5. A substrate is exposed at the outermost periphery by removing a recording layer at the outermost periphery by dropping a solvent on the outermost periphery of the substrate while rotating the substrate before forming the reflective layer. The method for manufacturing an optical recording medium according to claim 4, wherein a portion is provided. 6. The method for producing an optical recording medium according to claim 3, wherein the ultraviolet-curable resin used for the protective layer is a resin that dissolves 0.5% by weight or more of the recording layer material in an uncured state. 7. The method for producing an optical recording medium according to claim 6, wherein the ultraviolet curing resin used for the protective layer is a resin which dissolves at least 1% by weight of the recording layer material in an uncured state. 8. When the liquid resin used for the protective layer is applied, the recording layer protruding from the reflective layer in the inner peripheral portion is dissolved and removed in the liquid resin, and thus the protective layer is formed in the inner peripheral portion and the outer peripheral portion. 3. The method for manufacturing an optical recording medium according to claim 2, wherein both the films are formed so as to exceed the reflective layer. 9. The method for manufacturing an optical recording medium according to claim 2, wherein the substrate is a substrate made by injection molding a polycarbonate resin.